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nkhopkar1-Visitor
1-Visitor
November 13, 2016
Question

How to create a datum plane normal to an axis and tangent to a sphere

  • November 13, 2016
  • 5 replies
  • 11527 views

Hi All,

I have a sphere and an axis passing through that sphere. I want to create a datum plane such that it is normal to this axis and tangent to the sphere. Creo 3.0 won't allow me to select the axis and the surface at the same time. Am I missing something?

Thanks

Tangent.png

5 replies

R
RaphMORIN16-Pearl
16-Pearl
November 14, 2016

An idea... Select the axis, create the plane, define it normal then select the surface and define it tangent.

R
RaphMORIN16-Pearl
16-Pearl
November 14, 2016

I just tried my idea... it's not working !

R
RoyCrerar1-Visitor
1-Visitor
November 14, 2016

Hi,

The axis doesn't pass through the centre of the sphere. tangent and normal to axis can only be selected if the axis passed through the centre of the sphere.

N
nkhopkar1-VisitorAuthor
1-Visitor
November 14, 2016

Thanks for replying!

Unfortunately in my case the axis doesn't pass through the center.

KenFarley
KenFarley21-Topaz II
21-Topaz II
November 14, 2016

I think one of the troubles is that there are actually two solutions for the mathematical problem. The resultant plane may lie on either "side" of the sphere. Also, I've found the tangency constraint for these types of situations to be really flaky. The type of thing where it shows me the "correct" (expected) solution, but once I accept, the plane is on the other side of my geometry, etc. You might be forced to create a point at the desired side of the sphere and use that and the axis to define the plane.

N
nkhopkar1-VisitorAuthor
1-Visitor
November 14, 2016

Thanks for your answer!

I actually have a part of the sphere which is less than a hemisphere. So mathematically there should be only one plane which is tangential.

Tangent1.png

I want a plane normal to A_8 and tangential to the spherical tip.

I was hopping to avoid creating a point on the surface as it would mean a lot of geometrical calculations.

B
bgruman1-Visitor
1-Visitor
November 14, 2016

I know this isn't the "Magical" answer your looking for,  but I don't know how your gonna get where you want to go without additional construction geometry.

In this case,  I would Sketch a curve...   Normal to A_8 and Tangent to your dome...

Then create your plane Through the sketch curve,  and Normal to A_8.

Good Luck

Bernie

Bernie Gruman

Owner / Designer / Builder

www.grumancreations.com

T
TomD.inPDX17-Peridot
17-Peridot
January 1, 2017

Have you tried spherical coordinate system to define the plane?

And if not asked directly, the axis is normal to the sphere, right?

Otherwise there is no solution.

C
ckeller1-Visitor
1-Visitor
January 1, 2017

As I understood the question:

The solution is tangent to sphere, but not AT the point of intersection between sphere and axis.

T
TomD.inPDX17-Peridot
17-Peridot
January 1, 2017

Ah!  That opens up a few more possibilities.

K
Kevin1-Visitor
1-Visitor
January 4, 2017

A plane can only be made tangent to a surface if it is cylindrical or conical. You'll need to try another method to get the desired result.

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